My son also gets migraines and started them around 6 years old and they occur occasionally. He has had CAT scans and at this point in his life, his Doctor would just like to rule out any other concern so we are going to schedule an MRI. I really believe they are just migraines (certainly not to minimize "migraines", I would just rather it be that then a bigger medical concern.) My son is 11 years old. We, too, have had his eyes checked and he's had physicals, etc... and the pediatrician believes that they are migraines.
We've determined a few triggers: My son needs to eat regularly, including 2 snacks. He also needs to remember to stay hydrated, as he is the kind of kid who has a great metabolism, slender build and a lot of energy. And... he needs a good night sleep (he usually sleeps 9 - 10 hours) He does have seasonal allergies, so we, too, have him on Claritin OTC in the Spring and Fall, and if I notice any sinus concerns, he sometimes takes a nasal spray (Nasonex) for a 2 week stint. A young neighbor went through 3 months of torture because her migraines became so severe and debilitating that they couldn't go to school. A Doctor determined that this child had a gluten intolerance. Now that this child is off gluten, life is good. My sister's culprit for her migraines was dairy and has ended her love for cheese so, don't rule out food allergies that can develop at any time in your life.
For my son's migraines, he takes Jr. Strength Motrin/ibuprofen (300 mg's) at onset. Every year, I have to make sure to have the paperwork filled out to dispense medicine at school. This has been my biggest battle with my son, over the years. He would get a headache and "wait it out", thinking that it would just go away, or he doesn't want to bother anyone or he's a little embarrassed to tell the teacher. Unfortunately, this has lead to moments when he has come home from school in terrible pain, takes his ibuprofen, grabs his ice pack and goes straight to bed. When he is in that much pain, he occasionally vomits from them, too. Sadly, the medicine takes that much longer to kick in.
My son now has learned to IMMEDIATELY ask the teacher to go to the nurse's office, at onset, because he has a headache. He doesn't usually get auras (vision abnormalities /warnings) like I do (yes, family history is a biggie for a diagnosis, and I get them, too) but he gets other sensations and dull pain at onset. Most of his headache pain can be warded off immediately when he takes his medicine quickly. At the beginning of every school year, I talk to each of his teachers, then I write them a little note - "just an FYI that my son gets migraines, please let him get his med's when he asks." Otherwise, if you don't alert EACH teacher, they may view your child as trying to get out of an activity. Even then, I had a situation this year, when a teacher told my son that he only had "45 minutes left of school so please sit down". He didn't push the issue and he came home so terribly sick. I was so upset. The teacher later apologized to him - she just forgot about his history even though he had asked to go and see the nurse.
I'm telling you all this because he will be in school and you will want to arm him with something in school should he get a headache. No, I've never used feverfew but I wonder if a Dr. will sign permission to give this to your child during the school day. My son can go for weeks without getting a headache but, certain times of the year are worse for him.
So sorry to hear your son goes through this - it is awful to see them in pain. Just hopes this can help to minimize it.
Good luck.